The present invention broadly relates to collecting flexible folded products and pertains, more specifically, to a new and improved method of opening flexible folded products, which have been folded off-center. The present invention also relates to a new and improved apparatus for carrying out the inventive method.
The off-center or asymmetrically folded product possesses an open-edge region located opposite to the fold and comprises in this open-edge region a marginal lap at a first product portion, the marginal lap protruding beyond the other or second product portion.
Generally speaking, the method of the present invention is of the type according to which the flexible, off-center folded products are held at the off-center fold thereof and, in each case, at least the marginal lap of the off-center folded products is gripped or engaged by gripper jaws of a respective gripper of an opening device, the gripper jaws being movable in relation to each other.
In its more specific aspects, the new and improved apparatus for opening flexible asymmetrically folded products, such as printed products, each product having in an open-edge region, located opposite the off-center fold, a marginal lap at a first product portion, the marginal lap protruding beyond the other or second product portion, comprises holding means for holding or retaining the folded products at the respective off-center folds thereof, an opening device having at least one gripper with gripper jaws movable in relation to one another for gripping or engaging at least the marginal lap of a respective folded product, and bending means serving to bend or flex at least the first product portion engaged by the gripper, in order to at least partially lift off the two product portions from one another.
An example of an apparatus of this type for opening off-center folded printed products is known from European Patent Application No. 0,208,081, published Jan. 14, 1987 and the corresponding U.S. Pat. No. 4,684,117, granted Aug. 4, 1987 and assigned to the assignee of the instant application. In this prior art apparatus, the folded printed products to be opened are conveyed with the respective folded edges held by individually controllable grippers or clamps of a feeder. The direction of conveyance extends downwardly and inclinedly and the mouth or open jaw of the grippers is forwardly directed in the direction of conveyance, so that the open-edge region of the printed products conveyed in a downwardly and obliquely directed position or state is leading with respect to the folded edge located opposite the open-edge region. Below the feeder there is provided an opening device comprising holding clamps attached at uniform distances to a revolvingly driven traction element, these distances being smaller or shorter than the regular spacings between the grippers or clamps of the feeder. The traction element is guided at both ends over sprocket wheels, so that the active run extends approximately parallel to the direction of conveyance of the feeder. Each holding clamp comprises a stationary clamp support and a movable resilient clamping finger which is pre-stressed and, as seen in the direction of conveyance, is directed to the rear. In the region of the active run and of the sprocket wheel at the end of the opening device there is provided a support plate or panel for the leading edges of the printed products. In an embodiment with two chains arranged parallel to one another and provided with holding clamps attached to these chains, the holding clamps extend through longitudinal slots in the support plate, whereby the stationary clamp supports passing through these longitudinal slots are substantially in alignment with the support plate. Furthermore, co-rotating with the upstream sprocket wheel and connected thereto is a guide wheel. A round endless belt with an upper run upstream of the support plate is trained about this guide wheel. The printed products supplied by the feeder arrive with their respective open edges resting on the upper run of the round endless belt and are thereby brought into the correct position to be later retained by the holding clamps.
In the region of the linear or straight active run of the opening device, the movable resilient clamping fingers are raised or elevated from the stationary clamp supports by means of a guide cam and retained in an upper product-releasing position, so that--due to the lower circumferential speed of the holding grippers with respect to the conveying speed of the printed products--the leading marginal lap of the lower longer product portion protruding beyond the upper shorter product portion can move into the open holding clamp. In the transfer zone from the straight active run to the downstream sprocket wheel, the respective holding clamp moves out of the effective region of the guide cam, so that the movable resilient clamping finger moves downwardly as a result of its resilient elasticity into a clamping position and thereby holds the leading marginal lap. The holding clamp enters the guide region of the curved section of the support plate defined by the downstream sprocket wheel. The clamped leading marginal lap and, accordingly, the lower longer product portion is guidedly bent along the curved section of the support plate such that the shorter not retained product portion is urged to move away from the retained lower product portion and is thereby separated therefrom. A saddle-shaped support of a revolvingly driven collecting device moves into the opening formed by the two product portions which, subsequent to opening the related holding clamp, surround from above the respective saddle-shaped support. By opening the associated gripper or clamp of the feeder, the released printed product falls in a straddling manner onto the respective saddle-shaped support.
However, when the longer product portion possessing the leading marginal lap is on the upper side of the infed folded product, the feeder and the opening device have to be mutually synchronized such that the movable resilient clamping finger, upon being raised or elevated, lifts the marginal lap from below. As a result of the relative speed between the traction element of the opening device and the feeder, the open-edge region of the underlying shorter product portion comes into contact with the open movable resilient clamping finger or with respective stop elements or dogs. The clamping finger then moves into its clamping position and retains the shorter product portion which is moved as previously described along the curved section of the support plate. The longer product portion comprising the marginal lap thereby separates itself, by virtue of its inherent stiffness, from the bent shorter product portion retained at the curved support plate.
This known prior-art apparatus for opening printed products folded off-center or asymmetrically requires accurate synchronization between the feeder and the holding clamps of the opening device. In order to ensure under all conditions a reliable opening of all printed products, it is essential that the printed products to be opened meet exacting dimensional tolerances and assume a precisely defined position in the mouth of the respective holding clamps. This requires a corresponding constructional and manufacturing expenditure as well as considerable time-consuming adjustment work and extensive preparatory operations, especially in the case of change-over from one product size to another.
A prior art apparatus for collecting folded printed sheets and provided with a device for opening the non-centrally folded printed sheets conveyed while being retained or held at the fold thereof by grippers of an infeed device is known, for example, from European Patent Application No. 0,095,603, published Dec. 7, 1983 and the corresponding U.S. Pat. No. 4,489,930, granted Dec. 25, 1984 and assigned to the assignee of the instant application. Each gripper of the infeed device possesses a gripper mouth or jaw extending rearwardly with respect to the conveying direction of the collecting conveyor. Below the infeed device there is arranged the opening device which also comprises a revolving gripper belt at which holding clamps are spaced at essentially equal distances from one another like the grippers of the infeed device. These holding clamps of the gripper belt of the opening device serve in each case to hold the marginal lap of the upper longer printed-sheet portion overlapping the underlying shorter printed-sheet portion, while this shorter printed-sheet portion is moved away from the retained longer printed-sheet portion by means of a revolvingly driven small conveyor belt which follows the revolving gripper belt and travels at a considerably higher speed than the conveying speed of the infeed device. The trailing edge of the free shorter printed-sheet portion thereby drops to one side of an arriving receiving saddle. Thereafter, the holding clamp at the end of the gripper belt releases the trailing edge or marginal lap of the longer printed-sheet portion to drop to the other side of the receiving saddle which has been further displaced in the meantime. Finally, the associated gripper of the infeed device releases the printed sheet so that the same is positioned in a straddling fashion upon the corresponding receiving saddle under the action of its own weight. This known opening device of the prior-art apparatus for collecting off-center folded printed sheets is afflicted with essentially the same drawbacks and disadvantages as the aforedescribed prior-art construction disclosed in European Patent Application No. 0,208,081 and the corresponding U.S. Pat. No. 4,684,117.
An apparatus for opening printed products that have been inserted in radial direction into pocket-shaped compartments of a drum-type cell wheel is known, for example, from Swiss Patent No. 644,814, published Aug. 31, 1984 and the corresponding U.S. Pat. No. 4,398,710, granted Aug. 16, 1983 and assigned to the assignee of the instant application. Each printed product bears with the fold thereof upon the base portion of an outwardly open holder of a carriage at the rear end of each compartment partition wall and is held there by gripper jaws which press the printed product against a flange of the outwardly open holder. The inserted off-center folded printed product bears upon a support surface of a compartment partition wall by means of its longer product portion which possesses the marginal lap and thereby protrudes beyond the shorter product portion. To open the inserted off-center folded printed products, each compartment partition wall comprises at its outer edge two bending spring elements which cooperate with control cam surfaces of stationary cams and protrude by means of their free ends into the interior of the respective compartment. During rotation of the cell wheel, one bending spring element forming a pre-separation element and possessing an entrainment dog travels upon a control cam surface and is moved towards the open edge of the printed product, whereby the entrainment dog engages the marginal lap and entrains the lower longer product portion during its further forward movement. This results in a bowing-out or doming of the lower longer product portion. Accordingly, the upper shorter product portion is raised and a gap is formed between the two product portions which are to be separated from one another. The other bending spring element forming a holder element now travels upon the other control cam surface and its free end advances radially into the compartment and is thereby gradually lifted or elevated. This holder element enters the gap and engages below the raised upper product portion. During further rotation of the cell wheel the first bending spring element or pre-separation element with the entrainment dog is retracted from the compartment. The bowing-out of the lower product portion thus disappears, but the printed product is maintained open by the second bending spring element or holder element. In this known opening device located at the compartment partition wall of a cell wheel, it is necessary that the printed product bears upon a support surface and is not moved or displaced as long as the entrainment dog acts upon or engages the marginal lap of the lower or underlying longer product portion.